The objective of the proposed research is to further analyze the dynamic processes of mammalian ovulation. Special emphasis will be placed on the chemical changes which occur within the follicle as it approaches rupture. The research plan includes three general approaches to the problem: 1) Evaluation of ovarian collagenolytic activity during the ovulatory process: The proposed project will involve completion of the characterization of the collagenase activity which is expressed at pH 5.5 and 7.4. During this project period emphasis will be placed on the influence of collagenase inhibitors (particularly alpha2-macroglobulin) on ovulation. An effort will also be made to extract and purify this enzyme. 2) Evaluation of changes in the ultrastructure of follicles near ovulation: During the early stages of the proposed project, an ultrastructural analysis will be completed on follicles which have been inhibited from ovulation by indomethacin treatment. Subsequently, the major emphasis will be placed on an effort to localize the site of ascorbic acid in the follicle. 3) Evaluation of prostaglandins and smooth muscle contraction in ovulation: The proposed project includes experiments which would involve the direct injection of prostaglandins (and their inhibitors) into rabbit follicles, in vivo, to determine if prostaglandins (and their inhibitors) into rabbit follicles, in vivo, to determine if prostaglandins can induce ovulation by this approach. Also, tests will be run to examine whether prostaglandins can induce contractility in strips of hog follicles, in vitro. In additon, electronmicroscopy will be used to determine whether smooth muscle cells are common in the ovarian stroma around mature follicles.